ELECTRICIAN 2nd YEAR MODULE – AC / DC Motor Drives ONLINE TEST

Question 1 of 33

1. What is IGBT in VF drive?

Field supply switching device

Inverter switching device

D.C bus switching device

Rectifier switching device

Question 1 of 33

Question 2 of 33

2. Which is proportional to the torque in D.C motor?

Field current

Armature current

Back e.m.f

Terminal voltage

Question 2 of 33

Question 3 of 33

3. What is the purpose of LCD on basic operator panel in D.C drive?

Display availability of supply

Display the speed

Monitor the parameter

Indicate the fault

Question 3 of 33

Question 4 of 33

4. Why are A.C drives better suited for high speed operation?

No brushes and commutation

Robust in construction

Having lighter gauge winding

High starting torque

Question 4 of 33

Question 5 of 33

5. What is the disadvantage of DC drive?

More expensive than AC drive for high capacity motor

Installation of DC drives is more complicated

More complex with a single power conversion

Not suitable for high speed operation

Question 5 of 33

Question 6 of 33

6. What is the function of Field Supply Unit (FSU) in DC drive?

Produces required firing current to the firing circuit

Provides a constant voltage to the field winding of motor

Provides variable voltage to the field winding of motor

Provides a constant voltage to the armature of the motor

Question 6 of 33

Question 7 of 33

7. What is the name of the component marked as 'X' in the block diagram of AC drive?

D.C bus

Inverter

A.C motor

Rectifier

Question 7 of 33

Question 8 of 33

8. What is electric drive?

A device used as prime mover for generator

A device converts A.C to D.C supply

An electro mechanical device for controlling motor

A machine converts mechanical energy into electrical

Question 8 of 33

Question 9 of 33

9. What is the purpose of LCD in Basic Operator Panel (BOP) in AC drive?

Indicate the display error in reading

Indicate the incorrect operation of BOP

Indicate the status of drive

Monitor the parameter of AC drive

Question 9 of 33

Question 10 of 33

10. Which control system consumes very low power for motion control in AC and DC motors?

Armature control

Voltage control

Drives control

Field control

Question 10 of 33

Question 11 of 33

11. How can constant torque be obtained from armature and field controlled drives?

By increasing the field current

By controlling the armature voltage

By reducing the field current

By reducing the armature current

Question 11 of 33

Question 12 of 33

12. What is the name of the characteristic curve in D.C drive?

Torque Vs field current characteristic

Field current Vs armature current characteristic

Speed Vs torque characteristic

Speed Vs armature current characteristic

Question 12 of 33

Question 13 of 33

13. What is the purpose of JOG key in control panel of D.C drive?

Restart the motor

Stop the motor

Reverse the direction of motor

Inching operation

Question 13 of 33

Question 14 of 33

14. Which power modulator is used in the electric drive system?

Phase sequence indicator

Frequency multiplier

Cyclo converters

Servo controlled voltage stabilizer

Question 14 of 33

Question 15 of 33

15. Which type of machine in industries is provided with multi-motor electric drive?

Heavy duty electric drilling machine

Shearing machine

Air Compressor

Rolling machine

Question 15 of 33

Question 16 of 33

16. Why is it necessary to keep V/F ratio constant in a drive?

Maintain the rotor current minimum

Maintain the rated torque at all speeds

Maintain the speed of motor constant

Keep the stator flux maximum

Question 16 of 33

Question 17 of 33

17. Which drive is classified according to mode of operation?

Group drive

Individual drive

Continuous duty drive

Manual drive

Question 17 of 33

Question 18 of 33

18. What is the advantage of AC drive compared to DC drive?

Power circuit and control circuits are simple

Fast response and wide speed range of control

Installation and running cost is less

Requires less space

Question 18 of 33

Question 19 of 33

19. What is the full form of B.O.P in D.C drive?

Bridge Operator Programme

Basic Operation Programme

Bridge Operation Panel

Basic Operational Panel

Question 19 of 33

Question 20 of 33

20. What is the purpose of PROG/DATA button in BOP of AC drive?

To change the parameter setting

To display the data direction of rotation forward/REV

To display the data status of frequency and current

To store the entered data and factory stored data

Question 20 of 33

Question 21 of 33

21. What is the main use of A.C drive?

Control stepless speed in motors

Group drive motors

Interlocking system in industries

High starting torque

Question 21 of 33

Question 22 of 33

22. What is the function of power controller in drive circuits?

It detects the overloading condition of motor

It reduce motor current during transient operation

It sounds an alarm in no load conditions

It maintain the torque at low voltage conditions

Question 22 of 33

Question 23 of 33

23. What is the reason for using shielded cable for connecting low level signal circuits in DC drives?

Eliminates the electrical interference

Easy for connection

Good appearance

Protects from mechanical injuries

Question 23 of 33

Question 24 of 33

24. Which device controls the speed of A.C motor in A.C drive?

Speed feedback technology box

COMMS technology box

Microprocessor based electronic device

Field supply unit (FSU)

Question 24 of 33

Question 25 of 33

25. Which type of sensing unit is employed in drive systems?

Opto coupler

Speed sensing

Resistance temperature detector

Photo voltaic cell

Question 25 of 33

Question 26 of 33

26. How can the base speed of D.C shunt motor be increased by using D.C drive?

By increasing the supply voltage

By reducing the armature voltage

By increasing the field current

By reducing the field current

Question 26 of 33

Question 27 of 33

27. What is the function of IGBT in AC drive?

Stabilize the output voltage from the rectifier

Smoothening incoming A.C supply

Controls the power delivered to the motor

Converts incoming A.C power into D.C power output

Question 27 of 33

Question 28 of 33

28. What is the function of VSI drives?

Converts A.C to D.C

Converts D.C to A.C

Converts A.C to A.C

Converts D.C to D.C

Question 28 of 33

Question 29 of 33

29. Which is the classification of drive according to dynamics and transients?

Short time duty drive

Variable position control drive

Intermittent duty drive

Automatic control drive

Question 29 of 33

Question 30 of 33

30. Why are A.C drives mostly used in process plants?

Robust in construction

Easy to operate

Very high starting torque

Maintenance free long life

Question 30 of 33

Question 31 of 33

31. Which is the correct sequence operation of key button in BOP of AC drive to change the direction of rotation?

Press OFF → REV → ON

Press ON → REV → ON

Press ON → OFF → REV → ON

Press ON → REV → OFF → ON

Question 31 of 33

Question 32 of 33

32. Which is the application of single quadrant loads operating in first quadrant in drives?

Centrifugal pumps

Conveyors

Elevators

Hoists

Question 32 of 33

Question 33 of 33

33. Which control system is used for Eddy current drives?

Slip controller

DC chopper controller

AC voltage controller

Rectifier controller

Question 33 of 33